What are the types of PCB inks _ introduction to the role of pcb inks?

by：Rigao 2019-12-11

The concept of pcb ink PCB ink refers to the printed circuit board (
PrintedCircuitBoard, referred to as PCB)
The important physical characteristics of the ink used are the viscosity, thixotropy and fineness of the ink.
These physical characteristics need to be known to improve the ability to use ink.
Characteristics of pcb ink 1. Viscosity and thixotropy screen printing is one of the essential and important processes in the manufacturing process of printed circuit boards.
In order to obtain the fidelity of image reproduction, the ink must have good viscosity and suitable thixotropy.
The so-called viscosity is the internal friction of the liquid, which means that under the action of external force, one layer of liquid slides on another layer of liquid, and the friction force exerted by the inner layer of liquid.
The mechanical resistance encountered by sliding the inner layer of thick liquid is larger, and the resistance of thinner liquid is smaller. The unit of viscosity measurement is poop.
In particular, it should be pointed out that temperature has obvious influence on viscosity.
Thixotropy is a physical characteristic of liquid, that is, its viscosity decreases in the state of stirring, and its original viscosity is quickly restored after standing.
Through stirring, the thixotropy lasts for a long time, which is enough to reconstruct its internal structure.
In order to achieve high-quality screen printing effect, thixotropy of ink is very important.
Especially in the scraper process, the ink is stirred to liquidate it.
This effect accelerates the speed of the ink passing through the mesh and promotes the uniform connection of the ink separated by the original network cable.
Once the scraper stops moving and the ink returns to a static state, its viscosity will quickly return to the original required data.
2. Fine pigments and mineral fillers are generally solid. After fine grinding, the particle size does not exceed 4/5 microns and forms a homogenized flow state in a solid form.
Therefore, it is very important to require ink to have fineness.
Types of PCB ink is mainly divided into three types: Circuit, solder resist and character ink.
The line ink is used as a barrier layer to prevent corrosion of the line. When etching, the line is protected. It is generally liquid photosensitive.
There are two kinds of acid corrosion resistance and alkali corrosion resistance. Alkali resistance is more expensive. This layer of ink should be dissolved with alkali after corroding the outlet line.
The solder resist ink is used as a protective line on the line after the line is completed.
There are liquid photosensitive and heat curing, as well as ultraviolet hardening type, retaining the pad on the board, convenient for welding components, and insulation and anti-oxidation.
Character ink is used to mark the surface of the board, such as marking component symbols or something, usually white.
In fact, there are other inks, such as: peelable ink, which protects the parts that do not need to be treated when doing copper plating or surface treatment, and then can be torn off; Silver paste ink and so on.
Pcb ink use precautions, according to the actual experience of most manufacturers of ink use, the use of ink must be in accordance with the following provisions: 1. in any case, the temperature of the ink must be kept below 20-25 ℃, and the temperature change cannot be too great, otherwise it will affect the viscosity of the ink and the quality and effect of screen printing.
Especially when the ink is stored outdoors or at different temperatures, it must be placed at the ambient temperature for a few days or the ink barrel can reach the appropriate operating temperature before use.
This is because the use of cold ink will cause screen printing failure, causing unnecessary trouble.
Therefore, in order to maintain the quality of ink, it is best to store it in or under normal temperature process conditions.
2. The ink must be thoroughly and carefully stirred manually or mechanically before use.
If the ink enters the air, it should be allowed to stand for a period of time.
If dilution is required, it should be fully mixed before testing its viscosity. The ink bucket must be sealed immediately after use.
At the same time, never put the ink on the screen back into the ink barrel and mix it with unused ink.
3. It is best to use a cleaning agent that adapts to each other to clean the net, and it should be very thorough and clean.
When cleaning again, it is best to use a clean solvent.
4. When the ink is dried, it must be carried out in a device with a good exhaust system.
5. To maintain the working conditions should meet the technical requirements of the operation site to carry out screen printing operations.
What is the role of PCB ink in PCB manufacturing? Ink plays a role in protecting copper foil in manufacturing, leaving copper skin not exposed, which will affect the following processes, including photosensitive ink, carbon oil and silver oil, both carbon oil and silver oil have electrical conductivity. The colors of ink commonly used are white oil, green oil, black oil, blue oil, red oil and butter.